Re: Apple LLVM 10 and `__fallthrough__`

[Bruno Haible]

Alexei Podtelezhnikov wrote:
> > > Wiki suggests __apple_build_version__ >= 12000000
> > > https://en.wikipedia.org/wiki/Xcode#Xcode_11.0_-_14.x_(since_SwiftUI_framework)_2
> ...
> I wish I could directly test it. However, I could confirm that Swift
> release 5.3 (Xcode 12) was the first release with this line
> https://github.com/apple/llvm-project/blob/swift-5.3-RELEASE/clang/test/Sema/fallthrough-attr.c#L18

Thanks for the investigation. Although we can't test it, these are two
independent hints that __apple_build_version__ >= 12000000 is OK. Applied:


2023-02-28  Bruno Haible  <bruno@clisp.org>

        dfa: Tweak the last patch.
        Suggested by Alexei Podtelezhnikov <apodtele@gmail.com>.
        * lib/dfa.c (FALLTHROUGH): Assume that Apple clang, in C mode, supports
        __attribute__ ((__fallthrough__)) starting with version 1200.
        References:
        
https://en.wikipedia.org/wiki/Xcode#Xcode_11.0_-_14.x_(since_SwiftUI_framework)_2
        
https://github.com/apple/llvm-project/blob/swift-5.3-RELEASE/clang/test/Sema/fallthrough-attr.c

diff --git a/lib/dfa.c b/lib/dfa.c
index 994900fea2..20502a802f 100644
--- a/lib/dfa.c
+++ b/lib/dfa.c
@@ -69,7 +69,7 @@ c_isdigit (char c)
 #  define FALLTHROUGH [[__fallthrough__]]
 # elif ((__GNUC__ >= 7) \
         || (defined __apple_build_version__ \
-            ? __apple_build_version__ >= 14000000 \
+            ? __apple_build_version__ >= 12000000 \
             : __clang_major__ >= 10))
 #  define FALLTHROUGH __attribute__ ((__fallthrough__))
 # else